Thank youI wanted to know what is cover,effort,necessity because I could not locate in the course or in the Business Analysis practice guide

I got this question from my friend and I don't know the source

You have the below requirements for building a web application:Requirement A-Provide the ability to authenticate the user;Requirement B-Provide the ability to post to forums;You note that for the user to post to forums, he has to first login and beauthenticated.The relation between Requirement A and Requirement B is:a. Coverb. Subsetc. Effortd. Necessity

Necessity: A requirement and another related requirement must be implemented at the same time for a specific reason.

From the Business Analysis practice Guide, it is kind of implementation dependency. Without implementing login, user cannot post in forum.

For your ready reference, here are the details: (Definition is taken fromm BABOK,which is not reference for PMI-PBA)

Necessity: A requirement and another related requirement must be implemented at the same time for a specific reason.Effort: A requirement is easier to implement if a related requirement is implemented at the same time.Subset: A requirement is a decomposed outcome (one of the children) of another requirement. Cover: A higher-level requirement is the sum of its sub-requirements. In this case, all of the sub-requirements must be implemented in order for this higher-level requirement to be met. Value: Including a particular requirement increases or decreases the desirability of implementing a related requirement.